Cardiac muscles is the answer
        
             
        
        
        
They lay eggs because they don't have the genetics or things in their body to give birth.
        
                    
             
        
        
        
D I believe, in the picture that is attached explains
 
        
        
        
Trace fossils include footprints, trails, burrows, feeding marks, and resting marks. Trace fossils provide information about the organism that is not revealed by body fossils. Trace fossils are formed when an organism makes a mark in mud or sand.